Ppx deriving

[vasilisp]

This is a PPX version of our JSON deriving plug-in.

The generated code is somewhat different from the Camlp4 version. We follow the conventions of ppx_deriving, as opposed to the functorial style of (Camlp4) deriving.

The serialization format is the same, i.e., in principle you can dump x with Camlp4, parse the result with PPX, and get back x. Any divergence is a bug to be fixed.

I provide a few tests that demonstrate the syntax as a Gist.

[Drup]

Please add your tests directly in the repo.
I'll review later.

cc @whitequark it may interest you :)

[whitequark]

This is to differentiate between { x } and { x; _ }. The former has an exhaustiveness warning, turned off by default.

[whitequark]

LGTM, but camlp4 is not writhing enough in fiery hell

[hhugo]

Any update on this ?

[vasilisp]

@hhugo, the latest commits fix omissions discovered while testing in conjunction with Eliom PPX.

I guess nobody has felt the urge to merge this, but it should be merge-able.

[hhugo]

Can someone fix the code to remove the following warnings

ocamlfind ocamlc     -w +A-4-7-9-37-38-41-44-45 -w -40-42-48-27 -package ppx_deriving,ppx_tools,ppx_tools.metaquot -c ppx/ppx_deriving_json.ml
File "ppx/ppx_deriving_json.ml", line 108, characters 2-811:
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
Rinherit
  {ptyp_desc=(Ptyp_any|Ptyp_var _|Ptyp_arrow (_, _, _)|Ptyp_tuple _|
             Ptyp_object (_, _)|Ptyp_class (_, _)|Ptyp_alias (_, _)|
             Ptyp_variant (_, _, _)|Ptyp_poly (_, _)|Ptyp_package _|
             Ptyp_extension _)}
File "ppx/ppx_deriving_json.ml", line 245, characters 33-919:
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
Rinherit
  {ptyp_desc=(Ptyp_any|Ptyp_var _|Ptyp_arrow (_, _, _)|Ptyp_tuple _|
             Ptyp_object (_, _)|Ptyp_class (_, _)|Ptyp_alias (_, _)|
             Ptyp_variant (_, _, _)|Ptyp_poly (_, _)|Ptyp_package _|
             Ptyp_extension _)}
File "ppx/ppx_deriving_json.ml", line 34, characters 15-43:
Warning 26: unused variable lid.
File "ppx/ppx_deriving_json.ml", line 127, characters 27-54:
Warning 26: unused variable c.
File "ppx/ppx_deriving_json.ml", line 222, characters 12-13:
Warning 26: unused variable f.
File "ppx/ppx_deriving_json.ml", line 258, characters 13-55:
Warning 26: unused variable y'.

[vasilisp]

I will fix this ASAP.